Rotary kiln



i Oct. 28, 1930. R. w. P. HORN ET AL ROTARY KILN Filed Dec. 2 Sheets-Sheet l Oct. 28, 1930. R, W p HORN ET AL ROTARY KILN Filed Dec. 5, 1928 2 Sheets-Sheet 2 gwomtow WP f/of/i ingis most intense. y

p A still further object of the invention-1s tol Patented Oct. 28, 1930 STATES PATENT QPF-ICB f 1 '.RoBELaTIW. "1. HoRN,oF `A-LiJtN'io'wN;Aivnzrecoiifn. NissLEY, or MNHEImf l. p

. Y .PENNSYLVANIA Y ROTARY 'KILN Application med December 5.19am serial No; 32.45037.` 4l

l 'This invention relates to kilns of the rotary type intended for any purpose for which such kilns Ehave heretofore been used. y The embodiment. ofc-the inventionv disclosed in this.

ber'V 22nd, 1927.

' f Tlie primary object ofthe invention is to provide a kiln inwhieh high efficiency in the consumption of fuel7=maybe attained by vir-. tue of the manner by which.l the flow of fuelv and air` to supportl substantially complete'. combustion is controlled l a i y A further obj ect of the invention is to pro vide ajkiln provided with mechanism to supply `air to both ends thereof 1 in regulable quantities so that the 'combustion within v the kilnis withinlthe control'of the operator. Y

`Afuith'e'r obj ec't of the invention is to pro@ vide 'a kiln including means' to slow up or retard theflow o'fmaterial Vfrom its normalrate at the portion of the kiln at which the burnprovide a kilnin which the velocity ofthe gases resulting from the combustion is' reduced in order thatthe maximum hea-t con- 39 tained therein. may be utilized,` and inorder that particles of dust carried bythe gasv stieammaypbe permitted to settle out yof said stream before it passes vout of the stack.`

i A furtherlobjectoftheinvention-liesfin the 5:5; pro-duction of azkiln in which the flow Vof air,

fueland raw material to the kiln vis vaccomplished in anextremely practical'andsi'rn'pleY A still further-'object ofthe invention to provide a kilnhaving means to supplyvair at" 1 `Further objects of the invention 'will ap-` pearas a-description thereof proceedsfwith reference tothe accompanying drawings inVv which, Y,

,; .Figi sapfart side letatcn; part Ysectional? view ofthe improved kiln ofthis invention. Fig. 2is an enlargedj part `sectionaland part side eleva-tional view of the feeding end of the kiln.

Fig. 3 is a transverse section takenonfthe plane indicated by theline B-'B of Fig..2 lookingin the direction of the arrows. Q

YvkvFig. Lisa section Vof the kiln taken on'thieV plane indicated by the line A-fA in Fig. 2. s

Fig. c-is a longitudinal-sectional View of the burning endA of the kiln showing a slightly modified construction.I i

Fig. 6 is aisectional viewtaken onthe plane indicated byatheline C-C of Fig. 5 looking` inthe direction of the arrows..A 1' Fig. 7 is ari-.enlarged part-sectional view of the-discharge Vend ofthe kiln shown .in `Fia-1.l `Y i1 Fig.,8is a sectional vieu/A on theplane-indicated by the lineH-H on Fig; 1. v

. Like reference characters indicate like partsthroughout the several ligures. A y Referring tothe construction illustrated in Figs. l to 4, incl usive,.the improved kiln of y this application comprises Y an elongated shell llprovided with tires 11 serving as supports'.v forthe kiln during its rotation in well known manner. l' Said kiln is 'provided-with theiisual driving gear"l i12-that mesheslwithia suitable y driving pinion V`operatedljby any suitable motor arranged to rotate thelkiln relatively slowlyfduringthe Operation thereof. "The kiln eXtends'into 'open-ings 13 vof a'chamber 14 that-is in communication with arst'ack 15. As clearly illustrated in Figfl the end ofthe kiln extends beyond the rear. .wallof the chamber 14 and said end is provided. with the mechanism foiqsupplying the raw material byV aiIf to the kiln, as .hereinafterV described. The illustratedkiln is intended particularly for the burning' of cement,;but it' obviously,l may-be usedl for otherV purposes, such 4as the treatment vof ores and thebu'rning; of coke for example. y y

f `The feed' end' of 'they kiln is' shown. on an eiilargedgscale in FigQ. Asfsh'ownin said endfwith Va transverse partition: 16 secured to-the shell by angle irons 17 or in any other suitable manner. The walls: of the kiln. and

. gurefithe shell'l() yis provided adjacent its l r1 All i said partition may be lined with fire brick or other similar lining material 18. A raw material supply pipe 19 extends through an opening 20 provided in the partition 16 and its lining, said supply pipe having an angularly bent end 21 discharging its contents adacent the lining 18 of the kiln. Supply pipe 19 is closed at its opposite end by a plate 22 provided with an opening to receive an air supply pipe 23 connected at 24 to any suitable `supply of air under pressure. As clearly shown in Fig. 2 the air supply pipe 23er;- tends axially of the raw material supply pipe 19 and is provided with a multiplicity of discharge nozzles 25 inclined in thedirection in which the material is to be fed through pipe 19. The air supply pipe 24 may be provided with a control valve 26 of any suitable design.

The raw material enters the pipe 19 from al branch pipe 27 extending laterally therefrom and communicating with a` suitable hopper or other feeding arrangement. Feed pipes 19, 21, 27 and air supply pipes 23 and 24 remain stationary, and the kiln is arranged to rot-ate with respect to said pipes. In order to support the relatively large raw material supply pipes in the kiln suitable rectangular hollow boxes 28 are supported from the walls of the kiln by transverse members 294 rigidlyA united at their ends to said walls.

A supporting shell 30 is secured at one end to the side of one of said boxes 28 viewing Fig. 2, and extends through the other of said boxes 28 andissecured thereto in any approved 1, manner. Said shell is spaced from the supply pipe section 19 and roller bearings 31 and 32 are arranged in said space providing bearings permitting relatively free'rotation between the shell 30 carried by the kiln and the pipe section 19. It will be understood that the pipe 19 passes through the box 28 relatively'freely in order to permit the free rotation between said pipe and said box. In order to preventthe unrestricted flow of air into the kiln proper around the box 28 and through the opening 2O in the partition 16 of the kiln', suitable packing rings 33 and 34 attached to the shell 30 and the pipe section 19 respectively, are provided. Said rings permit relatively free rotation between said shell and pipe section.

Disposed across the kiln relatively close to the partition 16 is a brick 'or similar wall 35 as clearly shown in Fig. 3. Said wall is provided with openings 36, 37 and 38of any suitable form, but arranged adjacent the longitudinal walls of the kiln and constituting ports to supply the raw material to the kiln proper.

Vithin the chamber 14 the kiln is provided with gas outlets 39 and 40. The outlet 39 is spaced endwise of the kiln from outlet 40 and it isdiametrically opposite the lastmentioned opening for a purpose presently to be described. The openings of the kiln extend approximately through an arc of 150 and said openings are provided with linings 41 that extend a substantial distance into the interior of the kiln to provide shoulders 42 entirely around said openings. The wall of the kiln is so formed that no abrupt shoulders are provided in a direction circumferentially of the kiln. This is accomplished by gradually merging the lining for the openings into the side walls of the kiln as indicated at 43 (Figs. 2 and 4). Suitable angle irons 44 may be securedto the lining 10 of the kiln to attach the linings 41 to the kiln walls.

The wall of the kiln is preferably provided adjacent the chamber 14 with a lining 45 of gradually increasing thickness as clearly shown in Fig. 1. At intervals as shown at 46 said lining is sharply reduced in thickness providing shoulders at these points. Said lining may also be provided with projections 47, each extending through an arc of approximately 120 around the inner periphery of the kiln. Said projections however, are spaced laterally endwise of the kiln in order to permit the material to How around the ends thereof and into contact `with the adjacent spaced projection to be retarded thereby and subsequently discharged around the end or over the top thereof, as the material flows through the kiln as hereinafter more fully described.

It will be observed that the Vkiln is provided with gas outlet openings between its ends and means' is provided to supply air to the feed end of the kiln. It will be understood, however, that the amount of air supplied at that end of the kiln is under the control of the 0perator of the kiln. The discharge endof the kiln is constructed in order that the supply of air to this end may, likewise, be under the control of the operator.` Accordingly, the construction is such as to prevent substantial quantities'of air from entering the kiln at any point throughout its discharge end, and particularly through the discharge openings. In order that the material may be discharged without permitting the entry of substantial quantities of air at this point the kiln is provided with two annular closed chambers 48 and 48 surrounding the kiln adjacent the discharge end thereof. The chamber 48 communicates through an opening 49 with the interior of the kiln. The flow of material through said 'opening is controlled by a hinged door 50, whose opening movement is limited .by a chain 51' or in any other similar way. The material is discharged into the chamber 48 through the'opening 49 when the door 50, opening under the action of gravity, during the rotation of the kiln, assumes the position shown in Fig. 8. A discharge opening controlled by a door 52 similarly connectedito the out-er wall of chamber 48 controls the discharge of material from said chamber. t will be observed from Fig. l that the door 52 is diametrically opposite the door 50, so

that when the door is opened to discharge is closed While the discharge door 52 .is

opened. In this waly the contents of the material may be discharged from the kiln Without permitting substantialquantitiesof air to enter therein.- The chamber 48 is provided with similarly mounted doors 58 and 54 functioning in precisely the same manner, but it will be observed that the doorsA 50 and 53 are on diametrically opposite sides of the kiln and that the doors 52 and 54 are also so located. As a result, the chambers 48 and 48 discharge their material alternately at each half revolution of the kiln. The discharge eiid of the kiln is provided With a lined end Wall 55 and said. portion of the kiln carries a tivo-part shell including a portion 56 and a portion 57. The portion 56 is secured at one end to the end Wall 55 of the kiln and at'its other end to a box-like member 58 rigidly supported. in the Walls of the kiln. The section 56 is secured at one end to the box-like member 58 and adjacent its therend is supported in a similar boxA like supporting member 59, likewise rigidly secured in suitable manner to the side Walls of the kiln. An air conduit 60, arranged axially of the shell section 56is supported in said section by' suitable supporting elements, such as rings6l, arranged in the annular space between said shell section and said condiit. Said conduit is provided With suitable air discharge nozzles 62 'inclined in the direction of flow-of the fuel intothe kiln.

The fuel in the form of powdered coal, oil or any other suitable from is supplied to the kiln through a conduit 63 having 'a horizontal portion 64 extending throngh'the end Wall 55 of the kilu p Suitable packing rings are provided at 65 and carried bythe end Wall 55 and the .fuel supply conduit68, respective; Y

ly, `restricting the flow of airthrough said end wall along said 'conduit'. A portion of the conduit extending Within thekiln is supported on rollerbearings 66 disposed in thel space between the section 57 and said conduit, so that free rotation of the kilnyvith ree spect to said 'conduit can take place. An air supply pipe 68 controlled by a Asuitable valve 69 is provided With a horizontally extendingv portion 70 extending axially through the sec tion 64 of the fuel supply pipe. The portion 7()` extends Within the end of pipe 66 before 5 and 6, the kiln 10 is provided With discharge chambers 48 and 48" adjacent the discharge end thereof, that are similar in all respects to the discharge chambers illustrated on Fig.

1, and Vabove described and the loiv of the material from the kiln into said chambers and out of said chambers is controlled-by hinged covers or.. doors 56,j 52,. 53 and 54 as above described.' Attached to the end Wall 55 of the A kiln shown in these figures is a rectangular hollow box 7 3. The sides of said box" are eachprovided With aplurality of openings 745, each of which is controlled by a slidecover having a finger-holdv 76 to facilitate Vthe adjustment of said covers over the openings 7 4 in the box sides. Said box is -supported by legs 77 extending from each corner thereof'. Vand attachedin any suitablenianner tothe Wall of the kiln .(Fig.' 6).. `The end Wall 55 of the kiln is provided'Y with fa-.series ofair ports 78 opening into the interior of box 74. The other end Wall 79 of said box is provided with a circular opening() through `Which extends a fuel supply pipe 81'. Suitable inter Y locking ringsV 82 and V83 are carried by the box 73 and pipe 80 respectively, said rings serving to prevent the free flowl ofai'r along the fuel supply pipe into thekilnlY A vflanged fluid Vsupply pipe supporting shell 8.4 is securedA at one en'd to thevvall 79 of box 78, as shown at 851(Fig. 5)' and at its other end it is secured to a box-like support;- ing member 86 that is itselfisuitably secured to the Walls ofthe kiln as shown at 87. As'

illustrated in Fig5`,the shell 84 is of a larger diameter than lthediameter of the fuel supply pipe 181 and ball bearings 88 and 89 are.

frame 90 is' a supporting ring member 91V through Whichextendsa shell 92. One end of said shell is Vvflanged as shovvnlat 98..and said flanged end is secured to thebox-like supporting frame 86. vShell 9 2 serves as a support for an air supply pipe 94.arranged axially thereofand `supported .from the shell 92 by rings 95 and 96. Each off said rings is provided With a plurality of ports 97 permitting the flovv of fuel along the inner Wall of the shell 92 Said loW is caused byair under pressure projected from nozzles 98 carried by the closed pipe 94, said nozzles being inclined in the direction of flow of the fuel intofthe'burning zone of the kiln.

Air is supplied to the air supply pipe 94.

by an air conduit 99 that extendsaxially of the fuel supply pipe 8l and isprovide'dwith a multiplicity of nozzles 100,"each of which is inclined in the direction in which the fuel flows to the burning zone of the kiln. The air supply pipe 99 is secured to a plate 101 that closes one branch of a union 102 carf ried by pipe 81, another branch of which, 103,

provided with an adjustable baffle 106 of' frusto-conical form. Said baiie may be ad- `iusted on the pipe 99to bring it into proper position to cause the air discharged from the adjacent nozzles in said pipe to flow around the baille and through the annular space between the pipe 94 and the shell 92. The air supply pipe 94 and the shell 92 terminate adjacent a portion of the kiln that is of restricted diameter by virtue of the fact that it is provided near said point with a relatively thick lining 107. Immediately adjacent the discharge ends of pipe 94 and shell 92, said lining is gradually reduced in thickness,r asr shown, by forming the steps 108 terminating in a lining 109 that is sub stantially thinner than the lining portion 107.

Operation In operation the kiln 10 is set in slow rotation in well known manner. It will be observed that the longitudinal axis of the kiln is inclined from the feed end thereof toward the discharge end so that the raw material has a tendency to flow under the ac-V tion of gravity, from the feed end to the discharge end thereof. Kilns operating on this principle are well known. As shown in Fig. 1 the kiln extends in the chamber 14 leading to the stack 15 and the products ofV T he raw material is fed into the kiln adja-V cent the stack through the pipe 27. Said materi al enters the substantially horizontal portion 19 of the raw material supply pipe, and is caused to be carried therealong by air under pressure admitted through the nozzles 25. Air is thus positively mixed with the raw material supply ant said material and Y air enters the downwardly extending portion 21 and enters the kiln adjacent the 'partition 35. As the raw material and air enters said portion of the kiln the combustion that is taking place in the burning zone of the kiln causes flow of gases and partially burnt fuel toward the discharge openings 39 and 40. As the kiln is rotated the mixture of raw material and air admitted through the pipe 21 passes through the opening 36, 37 or 38 in the partition 35 successively in relatively small quantities. As the rawV material and air is thus charged into the portion of the kiln to the left of the partition 35, viewing Fig. 1, the air supplied causes the completion of the combustion of any unburned fuel about to be discharged into the chamber 14. Such combustion preheats the raw material. The How of air in a direction reverse to the flow of thc products of Combustion tends to retard their discharge to the stack and to thus cause dust to gravitationally settle on the raw material rather than be carried out through the stack. As said material moves along the kiln, as its rotation is continued, itis caused to pass around the openings 39 and 41, due to the fact that the inwardly projecting shoulders 42, surrounding said openings. prevent the discharge of said material from the kiln through said openings. lt will be readily understood that the height of the shoulders around said openings may be adjusted so that the material admitted suci cessively through the openings 30, 37 and 38 will not be caused to flow over the top thereof. As the rotation of the kiln continues the raw material continues to move toward the discharge end of the kiln and it is subjected to the highly heated gases coming from the burning Zone of the kiln, raising the temperature of the raw material as it moves along the kiln. As the movement of theY material continues it encounters the shoulders 47 which serve to momentarily retard the movement of the material endwise of the kiln thus maintaining the material for an appreciable interval of time at this point in the kiln. At the same time, said shoulders present an ol struction to the flow of the products of com bustion from the burning zone of the kiln. The flow of said products are further restricted by the one or more annular shoulders 46 provided approximately midway of the length of the kiln. As a result, substantial portions of dust carried by said gases are caused to be dropped upon the raw material through the kiln, thus preventing the escape of suc-h portions through the stack.

VWhen the raw material reaches the lirst shoulder 46 (Fig. 1) its movement is accelerated momentarily and it enters the burning Zone proper of the kiln. Said burning zone extends from said shoulder to the second shoulder 46 adjacent the discharge end of the fuel supply pipe 56 and the air supply pipe 60. Fuel and air under pressure are supplied in correct proportions to maintain Vio substantially complete combustion in this zone of the kiln and said fuel and air enter this portion of the kiln subjecting the matter contained therein to an intense heat. The spaced projections 47 tend to slow up or retard the flow of fuel and air suciently to permit substantially comp-lete combustion in the burning zone. As the raw material flows therethrough it is subjected to intense heat and when it encounters projections 47 its movement is retarded at the hottestpoint in the kiln. As the ravv material continues its flow along the kiln it passes over the shoulder 46 and into the cooling end of the kiln that surrounds the shell portions 56 and 57. As it further flovvs along the cooling end of the kiln it radiates heatthat raises the temperature of shell port-ions 56 and 57 to relatively high temperatures.causing a preheating of the fuel and of the air that passes axially through the air supply pipes and 60, thereby increasing the efciency of the apparatus by reclaiming the heat thus radiated. As the raW material continues its movement it reaches the discharge openings leading into the chambers 48 and 48 and it is discharged first into said chambers andafter the doors controlling the discharge of the material into said chambers are closed by the rotation of the kiln the material is discharged from the chambers Without admitting uncontrolled and uncontrollable quantities of air into the kiln While the material is being discharged therefrom. f

In the form of the invention shown in g the material moving toward the discharge openings of the kiln, shell portions 56 and 57 preventing combustion from taking place before the air and fuel is discharged from the shell 92 and the air pipe 94 respectively. As a result, Wh-en the fuel enters the burning zone that begins adjacent the end of said shell and pipe, the temperature of the air and fuel is such as to cause relatively complete combustion to occur as soon as said air and fuel enter this portion of the kiln. It is possible by this arrangement to obtain an extremely high eilciency.

Th-e invention may be embodied in other specific forms Without departing from the spirit or essential characteristics thereof. The present embodiment isV therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come Within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What We claim as our invention is:

l. A rotary kiln consisting of an elongated body substantially closed to the atmosphere at all points thereof, a chamber, a stack opening into said chamber, said kiln extending through said chamber and provided with openlngs arranged to be successively brought opposite the stack opening, and means to supply air and raW material to said body adjacent said stack, said air being supplied to cause combustion of unburned fuel or gases at this portion of the kiln, to heat the fuel entering said body.

2. A rotary kiln substantially closed to the atmosphere at all points thereof, one end of said kiln extending through a chamber, a stack opening into said chamber, the portion of said kiln extending through said chamber being provided with a plurality of discharge openings spaced endvvise of the kiln and on diametrically opposite sides thereof, and means Within said kiln around said openings to cause the material fed to said kiln to iioW around said openings.

ROBT. W. P. HORN. JACOB H. NISSLEY. 

